1. Field of the Invention
The present invention is directed to a method for producing an overall image from a number of partial images to be produced successively for common playback, and also is directed to an apparatus for implementation of the method. Such a method serves the purpose of matching images for the acquisition.
2. Description of the Prior Art
The format of X-ray film or of an image converter, such as a solid-state image converter or X-ray image intensifier, is not adequate for various radiological investigations.
In these instances, for example given a xe2x80x9cspine presentationxe2x80x9d, a number of exposures are made successively, the respective, resulting images then being electronically joined by means of a software program. The aiming device of the X-ray apparatus travels the length of the body region to be presentedxe2x80x94the spinal columnxe2x80x94for the exposures in this example, with an entire series of narrow images being made during this motion, and which are then combined with a specific software program at, for example, a workstation.
The spinal column thus can be presented as a whole and certain geometrical measurements can be implemented using specific measurement programs.
The apparatus motion in the exposure is synchronized with the image acquisition frequency, so that the registered partial images can be joined to one another without significant X-Y shifting.
A smaller X-ray detector, that may be too small for standard exposures, is usually employed in a lightweight and mobile apparatus.
A targeted control of the device for the registration of the partial images that is required for the composing, however, is not possible in the case of mobile apparatus.
When formats that are larger than the format of the X-ray detector are required, the manual registration of defined partial images is nearly impossible because overlaps, gaps or rotation or even variations in size that are too significant can arise between the partial images in the exposure.
An object of the present invention is to provide a method and an apparatus of the type initially described with which an easy setting of the exposure field is enabled in the successive exposures.
This object is inventively achieved by a method having the following steps:
a) producing a first partial image;
b) storing the first partial image;
c) playing back at least a part of the first partial image that adjoins a second partial image to be produced;
d) producing a survey image for the second partial image;
e) simultaneously playing back the survey image and the first partial image, whereby overlapping regions adjoin one another;
f) selecting the correct attitude of the exposure region for the second partial image;
g) placing the image acquisition device;
h) producing a second partial image;
i) joining the partial images to form the overall image.
The steps c) through h) can be repeated as warranted for further images with the second partial image used as the first partial image and a further image used as the second image.
As a result, partial images that have already been shot can be consulted in order to be able to select the correct image excerpt for the following exposure currently being obtained. For example, the edge zone of the partial image already registered is mixed in and the current transillumination image then shows the image excerpt selected as the second partial image.
It has proven advantageous to divide the overall image into a number of windows and to insert the exposures that have already been shot in respectively attitudinally correct positions in a window.
Inventively, the survey image can be produced as a single shot in transillumination mode or in an acquisition mode.
Alternatively, a real image, for example a photograph of the patient, can be produced in addition to the partial image, as a survey image in exactly the same projection corresponding to that of the first partial image.
The inventive diagnostic apparatus has an image acquisition device, an image system and a playback device and the image system includes:
a) a first partial image store connected to the image acquisition device;
b) a shift device connected to the first partial image store for playing back at least a part of the first partial image that adjoins a second partial image to be produced;
c) a mixing device connected to the image acquisition device for survey images of further partial images in addition to the reproduced part of the partial images already produced;
d) further partial image stores that are connected to the mixing device; and
e) an arrangement for joining the partial images to form the overall image.
A control device for the alignment of the image acquisition device can be allocated to the image system.